CVE-2020-26253 | .dev domains treated as local in Kirby

Kirby is a CMS. In Kirby CMS (getkirby/cms) before version 3.3.6, and Kirby Panel before version 2.5.14 there is a vulnerability in which the admin panel may be accessed if hosted on a .dev domain. In order to protect new installations on public servers that don't have an admin account for the Panel yet, we block account registration there by default. This is a security feature, which we implemented years ago in Kirby 2. It helps to avoid that you forget registering your first admin account on a public server. In this case – without our security block – someone else might theoretically be able to find your site, find out it's running on Kirby, find the Panel and then register the account first. It's an unlikely situation, but it's still a certain risk. To be able to register the first Panel account on a public server, you have to enforce the installer via a config setting. This helps to push all users to the best practice of registering your first Panel account on your local machine and upload it together with the rest of the site. This installation block implementation in Kirby versions before 3.3.6 still assumed that .dev domains are local domains, which is no longer true. In the meantime, those domains became publicly available. This means that our installation block is no longer working as expected if you use a .dev domain for your Kirby site. Additionally the local installation check may also fail if your site is behind a reverse proxy. You are only affected if you use a .dev domain or your site is behind a reverse proxy and you have not yet registered your first Panel account on the public server and someone finds your site and tries to login at `yourdomain.dev/panel` before you register your first account. You are not affected if you have already created one or multiple Panel accounts (no matter if on a .dev domain or behind a reverse proxy). The problem has been patched in Kirby 3.3.6. Please upgrade to this or a later version to fix the vulnerability.

Published: 2020-12-07 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2020-26253 is rated Moderate Risk (42.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.56%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-26253

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.16% 0.56% +0.40%
2 2025-03-17 0.09% 0.16% +0.07%
3 2023-03-07 0.09%

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-26253

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
2.2 4.0 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
2.2 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-26253

GitHub Security Advisory for CVE-2020-26253

GHSA-2ccx-2gf3-8xvv · Severity: medium · Ecosystem: composer — Kirby .dev domains and some reverse proxy setups were treated as local

Affected software / configurations for CVE-2020-26253

Vendor Product Version Raw CPE
getkirby kirby < 3.3.6 cpe:2.3:a:getkirby:kirby:*:*:*:*:*:*:*:*
getkirby panel < 2.5.14 cpe:2.3:a:getkirby:panel:*:*:*:*:*:*:*:*

References for CVE-2020-26253

cvelogic Threat Intelligence